Compressor



F. B. HUNT 4 COMPRESSOR Filcad Aug. 10, 1936 2 $hwts-Sheet 2 TToRNEYs.

Patented June 25, 1940 PATET OFFiCE COMPRESSOR Franklin B. Hunt,Chicago, Ill., assignor to lhe Liquid Carbonic Corporation, Chicago,111., a corporation of Delaware Application August 10, 1936, Serial No.95,083

5 Claims.

The present application relates to compressors, and more particularly tocompressors of the multi-stage type.

The primary object of the invention is to provide means whereby the 5number of stages of compression is greater than the number of Workingpistons in the complete machine.

A further object of the invention is to provide, in a machine of theclass described, means whereby, by a simple adjustment, the number ofcompression stages may be. varied, in a given machine.

To lated in the forms illustrated in the accompanying the accomplishmentof the above and reobjects, my invention may be embodied drawings,attention being called to the fact, however, that the drawings areillustrative only, and that change may be made in the specificconstruction illustrated and described so long as the scope of theappended claims is not violated.

l is a diagrammatic view of a two cylinder multi-stage compressor,

Fig. 2 is a diagrammatic illustration of a three cylinder compressorconnected in a car-- bon dioxide plant,

Fig.

3 is a view similar to Fig. 1, but showing a modified form ofcompressor, and

4 is a view similar to Fig. 2, illustrating illus- As is disclosed inthe copending application of Franklin B. Hunt, Jabez E. Pratt, Henry S.Tirrell and Robert L. Turner, Serial Number 686,486, for Method of andapparatus for producing carbon dioxide, one advantageous method ofmanufacturing liquid and solid carbon dioxide involves the steps ofcompressing gaseous carbon dioxide, in a multiple stage compressor, to apressure sufficient to cause liquefaction of gas, and passing the liquidthrough a series of successive evaporators, wherein portions of theliquid are evaporated to cool the remaining liquid; the finalevaporating stepv illustrated in the copending application causingsolidification of the remaining liquid. As is disclosed in saidcopending application, the gas evolved in the various evaporatingchambers is returned to the compressor at the various stages, the stageat which gas from a given evaporator is reintroduced into the compressordepending upon the pressure of the gas evolved in each individualevaporating chamber.

the drawings, the primary evaporating Hit.

Gas is evolved inthis chamber at a pressure of 300 pounds per squareinch. Gas is evolved in the secondary evaporating chamber IE2 atapproximately 75 pounds per square inch; and, during a freezingoperation, gas is evolved in the freezing chamber H63, likewise at apressure of approximately '75 pounds per square inch absolute.

However, after a suitable quantity of solid has been formed, it isnecessary to pump the freezing chamber pressure down to atmosphericpressure. Obviously, if gas at a pressure materially below '75 poundsper square inch absolute is to be led from the freezing chamber into thecompressor, and into a cylinder of the compressor which normallyreceives gas at a pressure of 75 pounds, the compression ratio in thatcylinder is greatly increased. When atmospheric conditions are reachedin the freezing chamber, that ratio of compression will be approximately20, which is excessive.

When a compressor of the type illustrated in Fig. 1 is used inconnection with such a plant, gas is led from the primary evaporatingchamber 16! to the high pressure cylinder H; and gas is led from thefreezing chamber W3 and/or from the secondary evaporator I62 to thecylinder l2.

This compressor comprises a driving means, indicated generally at ill,the two cylinders ii and i2 being positioned, in alignment, uponopposite sides of the driving means. A piston i3 is operativelypositioned in the cylinder ii and is connected by piston rod M, to thedriving means it]. Similarly a piston I5 is operatively positioned inthe cylinder I2 and is connected by a piston rod iii to the drivingmechanism it.

The cylinder ii is provided with a valved inlet port ll and a valvedoutlet port it at its end adjacent the driving means; and with a valvedinlet port l8 and a valved outlet port til at its end remote from thedriving means. Ob,- viously, because of the presence of the piston rodM, the effective cross-sectional area of that end of the cylinder I Iadjacent the driving means is less than the effective cross-sectionalarea of that end of the cylinder remote from the driving means.

Similarly, the cylinder I2 is provided with a valved inlet port 22 and avalved outlet port 2d at its end adjacent the driving means, and with avalved inlet port 2| and a valved outlet port 23 at its endremote fromthe driving means. In the same way the-eflective cross-sectional thedriving means is smaller than the effective A conduit 29 is providedwith branches com municating with the outlets 23 and it, and has a checkvalve 3% positioned therein, permitting flow away from the port 23, butpreventing fiow toward said port.

The conduit 29 leads to and through an intercooler 3|, and a conduit 32leads from the opposite end of said inter-cooler, being provided withbranches communicating with the ports El and E8 of the cylinder ii. Aconduit 33 connects the primary evaporator i8! with said conduit 32. Aconduit 3d leads from the ports is and 2d of the cylinder H, through acondenser It! to the primary evaporator i6.

While the freezing operation is going on, and gas is being supplied fromthe freezing chamber Hi3 through the conduit 25 at a pressure of 2'5pounds per square inch absolute, the compressor operates in a normalmanner, both of the cylinders l l and I2 operating as double-actingcompressors. This operation .will continue until the intake'pressure inthe conduit 25 falls below a predetermined value, such, for instance, as50 pounds per square inch absolute.

' A passage 35 communicates with the conduits 2i and 29; the point ofcommunication with the conduit 27 being between the valve 28 and theport 22, and the point of communication with the conduit 29 beingbetween the port 23 and the Valve 30. Flow through this passage 35 iscontrolled by a Valve 35, of any desired positively actuated type. Whenthe pressure in the conduit 25 falls below the predetermined value, thevalve 36 is opened; thereby converting the cylinder i2 into a two-stagecompressor, instead of a doub1e-acting compressor. With the valve 35open, gas will flow, upon movement of the piston 55 towardthe left, fromthe conduit 25 through the port 2! into the right hand end of thecylinder l2. Upon movement of the piston to the right, the gas in theright hand end of the cylinder will be forced through the port 23,conduit 29, passage 35, and conduit 27, and so through the port 22 intothe left hand end of the cylinder i2. Upon movement of the piston 25toward the left again, the gas so drawn through the port 22 will beforced through the port 2 and so through the intercooler 3i and to thecylinder H. Thus, gas is pumped from the right hand end of the cylinderl2 into the left hand end of said cylinder, which is of smaller volumebecause of the presence of the rod I6, and thence to the intercooler.Because of this difierence in the volumes of the respective ends of thecylinder l2, we get a two-stage compression which, when the intakepressure is 15 pounds per square inch and the pressure of discharge fromthe cylinder as a Whole is 300 pounds per square inch, involves acompression ratio of from 3 to 3 in the right hand end of the cylinderand a compression ratio of from 6 to 7 in the left hand end of thecylinder. Obviously, neither of these cylinder ratios is excessive, andinstead of approaching a zero pumping capacity due to low volumetricefiiciency,

the right hand end, with more than half of the total cylinder volume,operating with a ratio of 3 to 3%, will have a volumetric efficiency offrom 80 to 85%.

As soon as the pressure in the freezing chamber has reachedapproximately atmospheric value, the valve 36 will be closed and thenormal operation of the organization Will continue. Suitable valves are,of course, provided to control the flow through the system.

The above organization is, of course, merely a recompressor arrangement,into which carbon dioxide is introduced either in the liquid phasethrough conduit It? or in the gaseous phase through conduit I53; In Fig.2, there is shown a three cylinder combination compressor. In said Fig.2, the reference numeral it indicates driving mechanism, with which areassociated cylinders M, 2 and 43. All of the cylinders are in alignment,and the cylinder i2 is preferably positoned on one side of the drivingmechanism, while the cylinders M and 43 are positioned on the other sidethereof, the cylinder 575 being spaced from the driving mechanism by thecylinder M. A piston 44 is reciprocably positioned in the cylinder M andis carried upon a piston rod t5 connected to the driving mechanism. Anextension 45 of the rod 45 carries the piston 46 which is reciprocablymounted in the cylinder 33. A piston i! is operatively positioned in thecylinder 12 and is connected to the driving mechanism by a piston rod43.

Process gas (that is, gas which is'entering the conversion cycle for thefirst time) is led into the combination machine through the branchedconduit 49 which communicates witn'the valved inlet ports 50 and 5! ofthe first cylinder M which, operating as a double acting compressor,compresses the gas and forces it out through the ports 52 and 53 and thebranched conduit 54 to and through a first stage intercooler 55. Thence,the compressed and cooledgas, at 'a pressure of 50 to '75 pounds persquare inch absolute, is led through the conduit 56 to the inlet port5'! of the second cylinder 42.

Concurrently, gas from the freezing chamber I63 is led, through theconduit 58, to the valved inlet port 59 of the cylinder 32. An operatinghandle 53' is provided for manually holding open the valve in port 59,at times. The cylinder 12 operates as a double acting compressor,drawing gas for its left hand end from the cylinder ii, drawing gas forits right hand end from the freezing chamber H53 and secondaryevaporator I62; and forcing gas drawn from both sources through therespective outlet ports 5i and 62 and thus through the conduits 63 andii! to the second stage intercooler 58. A check valve 54 is interposedin the conduit 63, and a check valve 6i! is positioned in the conduit58, for a purpose which will later appear.

A passage 65 communicates with the conduits 58 and 63, the point ofcommunication with the conduit 58 being between the check valve E0 andthe inlet port 51, and the point of communication with the conduit 63being between the port 62 and the check valve 84. Flow through thepassage 65 is permitted or prevented, depending upon the position of acontrol valve 66.

From the second stage intercooler 68, gas is led through the conduit 69,at a pressure of approximately 300 pounds per square inch absolute.Concurrently, gas is led from the primary evaporator i6! through aconduit 1i and the conduit 89 joins the conduit H1 before said conduitll} ill) splits into branches II and I2 communicating, respectively,with valved inlet ports I3 and I4 of the cylinder 43. An operatinghandle I4 is provided for manually holding open the valve in port I4, attimes. Said cylinder 43, operating as a double acting compressor, forcesthe gas so fed to it through the valved outlet ports I5 and I6 and theconduit branches II and III to the high-pressure descharge line 70, thegas flowing through said line I9 at a pressure of approximately 1,000pounds per square inch.

When the complete organization is being operated to produce solid carbondioxide, the above description applies properly. As in the case of theorganization of Fig. 1, when it is desired to pump down the freezingchamber I63, the valve I50 is opened to provide an extra stage ofcompression in the cylinder 42.

If it is desired to operate the plant to make liquid carbon dioxide forsale, or if, for any other reason, the freezing chamber I03 is not inuse, manually operable means is provided for holding permanently openthe valves 59 and I4, thereby unloading the right hand end of thecylinder 42 and the left hand end of the cylinder 43, so that theorganization comprises a double-acting firststage and single-actingsecond and third stages.

The desirability of this arrangement is increased by the fact that thecylinder 4I cannot, in many instances, be used to pump down the freezingchamber to atmospheric pressure. In many commercial applications, thisfirst stage of compression has an intake pressure of 20 to 30 pounds persquare inch absolute; and. of

.' course, in such cases, it would be impossible to pump the freezingchamber down to a pressure below this value. In all cases where theprocess gas is coming from a chemical process, it is absolutelynecessary to avoid the building up of any increased suction pressure onthe first stage, since such an increase would affect the chemicalprocess. Thus, the combination disclosed in Fig. 2 not only eliminatesthe necessity for an additional cylinder in order to attain theadvantages of four-stage compression, but permits the handling of bothprocess gas and recompressed gas without affecting the chemical processsupplying the process gas.

In Fig. 3, I have illustrated a modification of the organization ofFig. 1. Driving mechanism is illustrated at and cylinders 8| and 82 arearranged in alignment on opposite sides of the driving means. A piston83 is operatively positioned in the cylinder III and is connected to thedriving means by a piston rod 84; and a piston 85 is operativelypositioned in the cylinder 82 and is connected to the driving means by apiston rod 06.

The cylinder BI is provided with valved inlet ports 01 and 38 positionedat its opposite ends, and with valved outlet ports 83 and 90, similarlyarranged. In the same way, the cylinder 82 is provided with valved inletports 9! and 92 and with valved outlet ports 93 and 94.

Gas from the freezing chamber or the secondary evaporator is fed to theport 9| of the cylinder 82 through a conduit 95 and its branch I36 andto the inlet port 92 through the branch 31 in which is positioned acheck valve 98. A

branched conduit 93 communicates with the ports 93 and 94 and leads gas,discharged from the I ports 93 and 94, into the intercooler IOI, a checkvalve I00 being positioned in the conduit 99. From the intercooler, gasflows through the conduit I02 to the inlet port 88 of the cylinder 8|,

being joined by gas flowing through the conduit I03 from the primaryevaporator. In the left hand end of the cylinder BI, the gas iscompressed and ejected through the port 00 and conduit I04 to andthrough the intercooler I and thence, through the conduit I06, whichjoins the conduit I0? leading from a sub-evaporator I60, to the inletport 81 at the right hand end of the cylinder 0|. Thence, the gas isejected at a pressure of from 1200 to 1400 pounds per square inch,through the port 89 and the discharge line I08.

As in the organization of Fig. 1, the cylinder 02 may be converted froma double-acting compressor to a two-stage compressor by opening thevalve H0 in the passage I09 which leads from a point in the conduit 09between the port 93 and the valve I00 to a point in the conduit 91between the valve 30 and the port 92. And, as in the case of Fig. 1,carbon dioxide is introduced into the system either in the liquid phasethrough the conduit IGI or in the gaseous phase through the conduit I68.

Fig. 4 is similar to Fig. 2, but incorporates the same modificationsfound in Fig. 3. Thus, the combination compressor of Fig. 4 comprises anoperating means I20, a first cylinder I2I, a second cylinder I22, and athird cylinder I23, said three cylinders being aligned and the cylinderI22 being positioned on one side of the operating means, with thecylinders I2I and I23 positioned on the opposite side of said operatingmeans, said cylinder I23 being spaced from the operating means by thecylinder I2I.

A piston I24 is reciprocable in thecylinder I2I, and is carried on apiston rod I25 connecting with the operating mechanism I20. Acontinuation I25 of the piston rod I25 carries the piston I26 which isreciprocable in the cylinder I23. A piston I2! is reciprocable inthecylinder I22 and is connected by a piston rod I28 with the operatingmeans I20.

Process gas is led into the combination compressor through a conduit I20having branches communicating respectively with the valved inlet portsI30 and I3I of the cylinder I2I. Said cylinder, operating as adouble-acting compressor, discharges the gas through valved outlet portsI32 and I33 to a conduit I34 which leads the gas to and through afirst-stage intercooler I35. Thence the gas, at a pressure of to 75pounds per square inch absolute, is lead by a conduit I36 to the inletport I3'I of the cylinder I22. Concurrently, gas from the freezingchamber IE3 or the secondary evaporator I02 is led through a conduit I38tothe inlet port I39 of the cylinder I22. Said conduit I30 continues tojoin the conduit I30 at the inlet port I3I, a check valve I40 beingpositioned therein between the ports I39 and I31. I

The cylinder I22, operating as a double-acting compressor, drawing gasfor its left hand end from the cylinder I2I and gas for its right handend from the freezing chamber or secondary evaporator, forces the gasthrough the valved outlet ports MI and I42 and through the conduits I43and I4? to and through the secondstage intercooler I48. A check valveI44 is positioned in the conduit I43 between the port I42 and theconduit I41. A passage I45 communicates with the conduit I43 at a pointbetween the port I42 and the Valve I44, and with the conduit I38 at apoint between the valve I40 and the port I31; flow of fluid through saidpassage being controlled by said valve I46.

Fromthe second-stage intercooler, the gas is led through a conduit M9,at a pressure of approximately 300 pounds per square inch absolute, to aconduit 550 leading from the primary evaporator IE! to the inlet portI52 of the cylinder 423. Gas entering the cylinder I23 through said portIE2 is compressed, upon movement of the piston 12$ toward the left, andforced through the outlet port I53 and conduit H54, thence through thethird-stage intercooler M5, and through the conduit 956 which joins witha conduit l5! leading from the sub-evaporator I66 to the inlet port 158of the cylinder 823, at a pressure of approximately 550 pounds persquare inch absolute. Thence, by a further compression stage achieved inthe right hand end of the cylin der I23, the gas is ejected through theoutlet port I59 and the high pressure line I60, at a pressure of1200-1400 pounds per square inch, to the condenser 564. The liquid thereproduced flows to the primary evaporator Nil.

As in previous examples, when it is desired to pump down the freezingchamber 463, the valve M6 is opened to provide two stages of compressionin the cylinder I22.

If it is desired to operate the plant to make liquid carbon dioxide forsale, or if, for any other reason, the freezing chamber IE3 is not inuse, manually operable means is provided for holding permanently openthe valves I30 and I52, thereby unloading the right hand end of thecylinder H2 and the left hand end of the cylinder E23,, so that theorganization comprises a double-acting first-stage and single-actingsecond and third stages.

While I have shown the piston rods of substantially uniform diameters inall the illustrated forms of my invention, it will be obvious that therods in a given form may vary in size. For instance, in the embodimentof Fig. 4, the portion of rod I25 which is located in cylinder E23 mightbe larger than the portion thereof which is located in the cylinder l2I. By this means, any desired ratio of cylinder size, within reasonablelimits, may be obtained.

I claim as my invention:

1. A compressor comprising a cylinder, a piston reciprocable in saidcylinder, a piston rod secured to one end only of said piston andprojecting through the adjacent end of said cylinder, a first valvedinlet port adjacent said end of said cylinder, a first valved outletport adjacent said end of said cylinder, a second valved inlet portadjacent the opposite end of said cylinder, a second valved outlet portadjacent said opposite end of said cylinder, a first conduit connectingsaid first inlet port with said second inlet port, a valve in said firstconduit preventing fluid flow from said first inlet port toward saidsecond inlet port but permitting fluid fiow in the opposite direction, asecond conduit connecting said first outlet port with said second outletport, a valve in said second conduit preventing fluid flow from saidfirst outlet port to said second outlet port but permitting fluid flowin the opposite direction, a third conduit communicating withv saidfirst conduit between said first inlet port and said valve in said firstconduit and communicating with said second conduit between said secondoutlet port and said valve in said second conduit, and-a valvecontrolling fluid flow in either direction through said third conduit.

2. In a device of the class described, a first cylinder, a first pistonin said cylinder, a second cylinder, a second piston in said secondcylinder, driving means interposed between said cylinders,

a third cylinder spaced from said driving means by said first cylinder,a third piston in said third cylinder, all of said cylinders beingaligned, a piston rod carrying said second piston and connected to saiddriving means, apiston rod carrying said first and third pistons andconnected to said driving means,-valved inlet and outlet ports ajacenteach end of each of said cylinders, a first branched conduit leadingfrom a fiuid source to both inlet ports of said first cylinder, a secondbranched conduit leading from both outlet ports of said first cylinderto theinlet port of said second cylinder adjacent said driving means,

a third branched conduit leading from a fluid source to the inlet portof said second cylinder remote from said driving means and, through acheck valve, to the inlet port of said second cylinder adjacent saiddriving means, a fourth branched conduit leading from the outlet port ofsaid second cylinder adjacent said driving means, and, through a checkvalve, from the outlet port of said second cylinder remote from saiddriving means, to the inlet portof said third cylinder remote from saiddriving means, a fifth conduit leading from a fluid source to saidfourth conduit, a sixth conduit leading from a fluid source to the inletport of said third cylinder adjacent said driving means, a seventhconduit leading from the outlet port of said third cylinder remote fromsaid driving means to said sixth conduit, and an eighth conduit leadingfrom the outlet port of said third cylinder adjacent said driving means.I

3. In a device of the class described, a first cylinder, a first pistonin said cylinder, a second cylinder, a second piston in said secondcylinder, driving means interposed between said cylinders, a thirdcylinder spaced from said driving means by said first cylinder, a thirdpiston in said third cylinder, all of said cylinders being aligned apiston rod carrying said second piston and connected to said drivingmeans, a piston rod carrying said first and third pistons and connectedto said driving means, valved inlet and outlet ports adjacent each endof each of said cylinders, a first branched conduit leading from a fluidsource to both inlet ports of said first cylinder, a second branchedconduit leading from. both outlet ports of said first cylinder to theinlet port of said second cylinder adjacent said driving means, a thirdbranched conduit leading from a fluid source to the inlet port of saidsecond cylinder remote from said driving means and, through a checkvalve, to the inlet port of said second cylinder adjacent said drivingmeans, a fourth branched conduit leading from the outlet port of saidsecond cylinder adjacent said driving means, and, through a check valve,from the outlet port of said second cylinder remote from said drivingmeans, to the inlet port of said third cylinder remote from said drivingmeans, a valve-controlled passage providing, at times, communicationbetween a point in said third conduit intermediate the check valvetherein and the inlet port of said second cylinder adjacent said drivingmeans, and a point in said fourth conduit intermediate the outlet portof said second cylinder remote from said driving means and the checkvalve in said fourth conduit, a

fifth conduit leading from a fluid source to said.

fourth conduit, a sixth conduit leading from a fluid source to the inletport of said third cylinder adjacent said driving means, a seventhconduit leading from the outlet port of said third cylinder remote fromsaid driving means to said sixth conduit, and an eighth conduit leadingfrom the outlet port of said third cylinder adjacent said driving means.

4. In a device of the class described, a first cylinder, a first pistonin said cylinder, a second cylinder, a second piston in said secondcylinder, driving means interposed between said cylinders, a thirdcylinder spaced from said driving means by said first cylinder, a thirdpiston in said third cylinder, all of said cylinders being aligned, apiston rod carrying said second piston and connected to said drivingmeans, a piston rod carrying said first and third pistons and connectedto said driving means, valved inlet and outlet ports adjacent each endof each of said cylinders, a first branched conduit leading from a fluidsource to both inlet ports of said first cylinder, a second branchedconduit leading from both outlet ports of said first cylinder to theinlet port of said second cylinder adjacent said driving means, athirdbranched conduit leading from afiuidsource to the inlet port ofsaid second cylinder remote from said driving means and, through a checkvalve, to the inlet port of said second cylinder adjacent said drivingmeans, a fourth branched conduit leading from the outlet port of saidsecond cylinder adjacent said driving means, and, through a check valve,from the outlet port of said second cylinder remote from said drivingmeans, to the inlet port of said third cylinder remote from said drivingmeans, a fifth conduit leading from a fluid source to said fourthconduit, a sixth conduit leading from a fluid source to the inlet portof said third cylinder adjacent said driving means, a seventh conduitleading from the outlet port of said third cylinder remote from saiddriving means to said sixth conduit, and an eighth conduit leading fromthe outlet port of said third cylinder adjacent said driving means, andmanually operable means associated with said inlet valve of said secondcylinder remote from said driving means and with said inlet valve ofsaid third cylinder remote from said driving means, and operableindependently to hold said respective valves open, at Will.

5. In a device of the class described, a first cylinder, a first pistonin said cylinder, a second cylinder, a second piston in said secondcylinder, driving means interposed between said cylinders, a thirdcylinder spaced from said driving means by said first cylinder, a thirdpiston in said third cylinder, all of said cylinders being aligned, apiston rod carrying said second piston and connected to said drivingmeans, a piston rod carrying said first and third pistons and connectedto said driving means, valved inlet and outlet ports adjacent each endof each of said cylinders, a first branched conduit leading from a fiuidsource to both inlet ports of said first cylinder, a second branchedconduit leading from both outlet ports of said first cylinder to theinlet port of said second cylinder adjacent said driving means, athirdbranched conduit leading from afiuidsource to the inlet port ofsaid second cylinder remote from said driving means and, through a checkvalve, to the inlet port of said second cylinder adjacent said drivingmeans, a fourth branched conduit leading from the outlet port of saidsecond cylinder adjacent said driving means, and,

through a check valve, from the outlet port of said second cylinderremote from said driving means, to the inlet port of said third cylinderremote from said driving means, and a fifth conduit leading from theoutlet port of said third cylinder remote from said driving means to theinlet port of said third cylinder adjacent said driving means.

' FRANKLIN B.'HUNT.

